cooling_systems Flashcards
What type of systems are most commonly used for cooling?
Air-based systems, especially in commercial settings.
What are ‘tons’ in cooling systems?
A ‘ton’ refers to 12,000 BTUH of cooling capacity.
How many CFM is typically associated with one ton of cooling?
About 400 CFM.
What is a typical rule of thumb for cooling in terms of building area?
300 sq ft per ton (ranges from 200-600 depending on use).
What effect does air-based cooling have on moisture in the air?
Cooling systems automatically dehumidify the air.
Why does condensate form in a cooling system?
As air cools, it can’t hold as much moisture, leading to condensate on the coil.
What makes refrigerants useful for cooling?
They undergo phase changes at useful temperatures and pressures.
What is the function of a compressor in a cooling loop?
It increases the pressure and temperature of the refrigerant.
What is the function of an expansion valve in a cooling loop?
It decreases the pressure and temperature of the refrigerant.
What are the main components inside an AHU?
Fan, coil (hot/cold), filters, and sometimes humidification/dehumidification elements.
What is the purpose of supply and return ducts?
Supply delivers conditioned air to spaces; return brings back used air for reconditioning.
What are key rules for duct design?
Avoid crossing supply and return trunks, minimize elbows, and balance duct lengths.
What is a plenum?
An architectural space used to return air without dedicated ductwork.
What is a disadvantage of plenum return systems?
Reduced acoustic separation between spaces.
What are the four loops in a full cooling system?
Refrigerant loop, heat rejection loop, chilled water loop, air side loop.
What is the function of the heat rejection loop?
Moves heat from the refrigerant to the cooling tower and then outside.
What is the function of the chilled water loop?
Distributes cooled water to air handling units to condition air.
What is the function of the air side loop?
Moves air through the AHU to the space and back for reconditioning.
What does DX stand for and when is it used?
Direct Expansion; used when refrigerant directly cools the AHU without a chilled water loop.
